With the rapid development of display technologies, display apparatuses with touch function are becoming more and more popular due to their advantages such as visualized operation. According to different relative positions of the touch screen panel relative to the display panel, existing display apparatuses with touch function can be generally classified into two categories, the on cell touch screen panel and the in cell touch screen panel. Compared with the on cell touch screen panel, the in cell touch screen panel has smaller thickness and higher light transmittance.
As for existing display apparatuses, the OLED (Organic Light Emitting Diode) as a current type light emitting device is more and more applied to high performance display areas due to its characteristics such as self light emitting, fast response, wide angle of view and ability of being fabricated on a flexible substrate. According to different driving manners, OLED display apparatuses can be classified into two categories, the PMOLED (Passive Matrix Driving OLED) and the AMOLED (Active Matrix Driving OLED). The AMOLED display is expected to become the next generation new flat display in place of the LCD (Liquid Crystal Display) due to its advantages such as low fabrication cost, high response speed, low power consumption, DC driving applicable to portable devices, large operating temperature range. In existing AMOLED display panels, each OLED is driven to emit light by a pixel driving circuit composed of multiple TFT (Thin Film Transistor) switches within one pixel unit on the array substrate to realize display. The pixel driving circuit directly determines the quality of the light emitting display of the OLED. Therefore, the design of the pixel driving circuit is key technological content of the AMOLED.
On the other hand, the in cell TSP (Touch Screen Panel) fabricates a sensor for touch and a driving circuit in each pixel unit on the array substrate by the array process as well. If the sensor and the driving circuit of TSP are superimposed in an AMOLED pixel unit, it is necessary to add a certain number of driving circuit TFTs. Therefore, certain space of the pixel unit needs to be occupied additionally, but the free space in the pixel unit is limited. This dramatically limits the simultaneous fabrication of the in cell touch screen panel circuit and the AMOLED driving circuit.